Recently, thin-film devices using organic semiconductor materials, such as organic EL (Electro Luminescence) devices, organic FET (Field Effect Transistor) devices, and organic thin-film photoelectric conversion devices, are getting attention, and become in a practical use.
The mobility of electronic charge carrier (hereinafter, simply referred to as a carrier) is important in the basic physicality of the organic semiconductor materials used for such thin-film devices. For example, in the case of an organic EL device, the mobility of carrier affects the transportation efficiency of charge. The transportation efficiency of charge is important for improvement of the luminescent efficiency and for the low-voltage driving. Moreover, in the case of an organic FET device, the mobility of carrier directly affects the switching speed of a transistor and the performance of a device to be driven. Hence, the mobility of carrier is also important for the practical use of an organic FET device and the improvement of the performance.
Under such a circumstance, various organic compounds available as the organic semiconductor materials are researched and exploited. Compounds having a benzene-thiophene skeleton are studied as compounds having an appropriate carrier mobility. Non-patent Literature 1 exemplifies compounds having various benzene-thiophene skeletons.